1. Technical Field
The present disclosure relates to a touch sensor embedded display device, in which touch sensors are embedded in a pixel array, and a method for driving the same.
2. Discussion of the Related Art
User interfaces (UIs) are configured so that users are able to communicate with various electronic devices, and thus can easily and comfortably control the electronic devices as they desire. Examples of UIs include a keypad, a keyboard, a mouse, an on-screen display (OSD), and a remote controller having an infrared communication function or a radio frequency (RF) communication function. User interface technology has continuously expanded to increase user's sensibility and handling convenience. UIs have been recently developed to include touch UIs, voice recognition UIs, 3D UIs, and the like.
The touch UI has been adopted in portable information devices, such as smart phones, and use of the touch UI has been expanded to include notebook computers, computer monitors, and home appliances. A technology (hereinafter referred to as “in-cell touch sensor technology”) has been recently proposed to embed touch sensors in a pixel array of a display panel. In the in-cell touch sensor technology, the touch sensors may be installed in the display panel without an increase in a thickness of the display panel.
In the in-cell touch sensor technology, electrodes connected to pixels of the display panel are used as electrodes of the touch sensors. For example, the in-cell touch sensor technology segments a common electrode supplying a common voltage to pixels of a liquid crystal display and uses segmented common electrode patterns as the electrodes of the touch sensors.
The related art in-cell touch sensor technology time-divides one frame period into a first period (hereinafter referred to as “display period”), in which the pixels are driven, and a second period (hereinafter referred to as a “touch period”), in which the touch sensors are driven, and drives the touch sensors only during the touch period. In the related art in-cell touch sensor technology, a touch report rate is set to be the same as a display frame rate. The touch report rate indicates a frequency at which coordinate data obtained by sensing all of the touch sensors present in the display panel is transmitted to an external host system. The display frame rate indicates a frequency at which all of the pixels present in the display panel are updated to new data. As the touch report rate increases, a time required to update coordinates of a touch input is reduced. Therefore, touch sensitivity a user perceives can be improved, and a touch input trace can be represented in detail. However, because the related art in-cell touch sensor technology recognizes the touch input at the touch report rate, which is set to be the same as the display frame rate, it is difficult to implement a fast response of the touch input.
The related art in-cell touch sensor technology may consider increasing a length of the touch period in a fixed length of one frame period to increase the touch report rate. In this case, a length of the display period has to be reduced based on the increase in the length of the touch period. However, an excessive reduction in the length of the display period leads to a reduction in display quality of an input image due to a shortage of a charge time of the input image.